Clutch construction



June 9, 1936. R. c. RUSSELL 2,043,812

CLUTCH CONSTRUCTION Original Filed Aug. 21, 1933 2 Sheets-Sheet l A IINVEAITOR. E. ffaevi C ffusseZZ,

A TTORNEYJ Jung 9, 1936. c RUSSELL 2,043,812

' CLUTCH CONSTRUCTION Original Filed Aug. 21, 1933 2 Sheets-Sheet 2 E :Lg. E

a VI I i a e) /42 INVENTOR.

Robert" C. fiaasel Z.

ATTORNEYG.

Patented June 9, 1936 UNITED STATES PATENT OFFICE CLUTCH CONSTRUCTIONRobert C. Russell, Detroit, Mich.

19 Claims.

This invention relates to clutches and particularly to clutches of thetype adaptable for use between the engine and transmission of motorvehicles, the principal object being the provision of a clutch which maybe operated with a minimum expenditure of energy on the part of theoperator, and is a division of my application for Letters Patent of theUnited States for Improvements in clutches filed August 21, 1933, SerialNumber 686,019, issued July 24, 1935 as Patent No 1,957,563.

Other objects include the provision of a servo mechanism for efiectingdisengagement of a clutch; the provision of a clutch in which powerderived from the driving member may be employed for moving the clutch toreleased position; the provision of a clutch having spring meansnormally urging it toward engaged position and friction means under thecontrol of the operator of the clutch enabling the operator to tap thepower in the driving member and apply it to the operation of moving theclutch to released position; and the provision of a clutch having aservo mechanism associated therewith so constructed and arranged thatthe operation of the clutch either to or from engaged position is at alltimes under absolute control of the operator whether the driven memberis rotating or not, including a pilot or auxiliary friction device bothmembers of which are bodily movable and one of which members being sorelated with respect to the other thereof that relative rotation betweenthem causes axial movement of one relative to the other, and menu .13controllable friction means associated and bodily movable with theaxially movable one of said cam members whereby the rotation thereofrelative to the other may be retarded in a controlled manner thereby tocause the desired movement of the clutch throughout relative axialmovement between said cam members; the provision of a plate clutchhaving a cam member provided with an axially disposed cam surface fixedfor equal rota ion with the driving element of the clutch and a secondcam member normally rotatable with but also rotatable relative to thefirst cam member, anti-friction means being interposed between theaxially directed cam surfaces of said cam members and the cam membersbeing so formed that upon relative rotation between them axial movementis imparted to one of them, and manually controllable means frictionallyassociated with one of said cam members whereby to enable retardation ofits rotation relative to the other thereof and through relative axialmovement between the cam members cause disengagement of the clutch.

Other objects include the provision of a plate type of clutch having anovel form of servo mechanism to effect disengagement thereof and including a pair of associated rings, one of which is fixed for equalrotation with the driving memher of the clutch, and the rings beingprovided with complementary axially disposed inclined surfaces at theiradjacent ends, anti-friction means being provided between thecomplementary inclined surfaces and means being provided for effectingrelative rotation between the rings.

whereby to cause axial displacement of one with respect to the other;the provision of a mechanism as above described in which the inclinedteeth are so shaped as to cooperate with the antifriction means to limita relative rotation between the rings.

Other objects include the provision of a novel servo mechanism forclutches including a pair of relatively rotatable members havingcomplementary inclined teeth, the teeth being inclined at varyingdegrees between their end surfaces whereby to enable the desired degreeof axial movement to be obtained between them while permitting them tobe maintained in axially displaced relation with a minimum of efiort.

Other objects include the provision of a novel servo mechanism foroperating a clutch so designed as to permit actuation of the clutchmanually without the aid of the servo mechanism.

Further objects include the provision of a plate type of clutch havingspring means for indirectly clamping the clutch elements togetherincluding co-acting cam elements constantly urged toward one directionof rotation with respect to each other, and means frictionallyassociated with one of the cam elements capable of being actuated tocause relative rotation betweenthe members in a direction opposite tothat ,in which they are normally urged, thereby to effect release of theclutch.

The above being among the objects of the present invention the sameconsists'in certain novel features of construction and combinations ofparts to be hereinafter described with reference to the accompanyingdrawings, and then claimed, having the above andother objects in view.

In the accompanying drawings which illustrate suitable embodiments ofthe present invention and which like numerals referto like 'parts 7throughout the several different views.

Fig.1 is a partially broken, partially sectioned View of a clutch takenin a vertical plane including the axis thereof, the clutch being shownin engaged position.

Fig.2 is a fragmentary vertical, transverse sectional view taken on theline 22 of Fig. 1.

Fig. 3 is an enlarged end View of'one of the cam rings. V

Fig. 4 is a side elevational view of the cam rings and cooperating ballmembers in a position in which the rings are separated a maximum amount.r I a r a Fig. 5 is a fragmentary, partially sectioned, side elevationalview of the servo mechanism for the a clutch shown in Fig. 1illustrating the position of r the parts thereof when the clutch isdisengaged solelyby manual pressure. 7 V

Fig. 6 is a vertical sectional view taken longitudinally through amodified form of clutch construction.

Fig. 7 isa verticaltransverse sectional view taken on the line 1-1 ofFig. 6..

,While the present invention is applicable to clutches regardless oftheir use, as will be readily understood by those skilledin the art, itis particularly adaptable for use in connection with motor vehicles andfor that reason and'for the purpose of illustrating one'suitable useonly its application to motor vehicles will be referred to herein. 7 a

. ;As is well understood by those skilled in the motor vehicle art, thepresent trend of design is toward more powerful engines, and reducedoverall height of the vehicle which means decreased ground; clearance.Theincreasedpower of the vehicle demands a clutch capable of handling'anV increased load and the reduced ground clearance demands a clutch ofminimum diameter whichin turn requires higher clutch pressures. Wheresuch a clutch is released purely through manual pressure as in themajority of conventional constructions,;and due to the limited amount ofpermissible pedal travel for the clutch operating;

lever, it is obvious that the pedal pressure required to operatetheclutch becomes, exceedingly large, in fact" so great that in manystructures now on the market it becomes exceedingly tiresome to theoperator where he is required tocon- V tinuously operate'the clutch. Atthe same time,

not only is it tiresometo operate clutches requiring heavy pedalpressure but such pressure detracts from the desired accuracy of controlwhich clutch action.

is necessary in most cases, to obtain a smooth 1 Recently attemptshavebeen made to overcome the disadvantage of the manual operation ofactual controlof the engaging movements of the clutch, which bringsabout an undesirable con-' dition particularly inview of the factthat'clutch engagement requirement at one speed position of' thetransmission is necessarily different from that; :at another speedposition of the transmission? s In accordance with the' presentinvention a construction is provided wherein, regardless of the actualamount; of force necessary to separate thrust bearing 58.

the driving and driven elements of the clutch, the vehicle operator mayeffect either engagement or disengagement of the clutch through a footpedal without requiring the expenditure of more than anominal amount ofenergy on his 5 part, and at the same timemovements of the ing thisresult power to operate the clutch is derived from the driving member ofthe clutch which of course is directly connected to the ve-' hicleengine, through the employment of an auxiliary or pilotclutch-likeapparatus which requires aminimum amount of energy for its operation. 7

Referring now to the drawings, and particularly to Figs. 1 to 5inclusive, an engine crank shaft is indicated at In having a flange l2formed on its rear end which is secured to the web I4 of a flywheelhaving a rim l 6. The clutch housing surrounding the flywheel isindicated at l8 to the rear face of which is secured as by means of capscrews 20 the bell housing portion 22 of a transmission casing 24.Rotatably mounted in the front Wall 26 of the transmission casing 241s ashaft 28 which projects forwardly therefrom and its forwardly reducedend is rotatably supportedby a bearing Bllmounted within the rear end ofthe crank shaft H1 in a conventional manner. Immediately rearwardlyofthe flange I2 of the crank shaft lo the shaft 28 is splined as at 32 jand slidably but nonrotatably received thereon is a hub 34 of a clutchdriven member 36 provided on opposite faces with a suitable frictionmaterial 38 in accordance with conventional practice. Secured tothe rearface of the rim l6 of the flywheel as by cap screws 40 is a clutch cover42," shown as being formed, from sheet metal, and 40 extending firstradially inwardly of the rim I6 of the flywheel, then approximatelyaxially in a rear-- ward direction as at 44,'and then again radiallyinwardly as at 46. A pressure plate 48 of ringlike formation islocatedbetween the cover 42 and the clutch driven element 36 andaplurality of coil springs 50 constantly maintained under compressionbetween the wall 46 of. the clutch cover 42 and the pressure plate 48constantly urge the pressure'plate 48 toward the web I4 of the flywheelso as to clamp the driven disc 36 therebe tween for equal rotation,therewith. Suitable V 7 means, not shown, connect the pressure plate 48to the fiywheel'for equal rotation therewith but permit relative axialmovement between them in accordance with conventional practice.

A plurality of axially parallel rearwardly projecting studs 52 arethreaded into the pressure plate 48 adjacent the outer edge thereof andproject through the radially extending outer portion of the clutch cover42. A radially extending clutch finger 54 is slidably received adjacentits outer end upon each of the studs 52 and projects radiallyinwardlytherefrom Y through an opening 56 inthe portion 44 of theclutch cover 42and into a'position where its inner end may be readily engaged by theclutch throwout of An abutment for each of the fingers 54 is provided onthe corresponding stud "52 in the form of an adjustable nut 60, and acoil 70 7 spring 62 surrounding each stud 52 is maintained undercompression between the corresponding finger 54 and the pressure plate"48 to maintain the finger against the abutment and to aid in.

light coil spring 64 is provided between each finger 54 and. the rearwall 46 of the clutch cover 42 to further aid in preventing rattling ofthe fingers 54 during operation of the clutch.

The construction thus far described is entirely conventional and as faras the present invention is concerned, any other similar conventionalconstruction may be employed in its place.

In accordance with the present invention a member 66 is fixed to thepressure plate 48 as by means of screws 68 and is provided with arearwardly extending sleeve I0 concentric with the shaft 28 andpreferably radially spaced therefrom as indicated. The bearing 58 is'shown in the present case as being rotatably and slidably mounted uponthis sleeve I0. Relatively nonrotatably but axially slidably mounted onand adjacent the rear end of the sleeve I9 and maintained againstrearward movement thereon by means of a nut I2 which may also beemployed for compensating for wear of the clutch facings 38, is a member14 in the form of a ring, the axially forward face of which is providedwith a plurality of equally angularly arranged axially inclined surfacesor teeth I6, two of such teeth being shown as preferable, although moremay be used in some cases. Another ring member I8 is rotatably andaxially slidably mounted on the sleeve I9 forwardly of the ring I4 andits rear axial face is provided with two equally angularly spacedinclined surfaces or teeth 89 complementary in inclination and angularextent to the teeth I6. Suitable anti-friction means, illustrated as aplurality of bearing balls 82, are interposed between opposed teeth I8and 98 and are maintained in equally angularly spaced relation about theaxis of the shaft 28 by a retainer 83 of plate-like form. Assuming thatthe clutch turns in the conventional direction, that is, in a clockwisedirection as viewed from the right hand end of Fig. 1, then the teeth I6and 89 are inclined in a direction corresponding to that of a right handthread, and where the bottom of one tooth joins the top of the adjacenttooth the rings I4 and I8 are radiused as at 85 an amount correspondingto the curvature of the balls 82 so as to form a reverse movement stoptherefor as will hereinafter be more fully brought out.

To the forward face of the member I8 is fixed a disc 84, bodily movabletherewith, in the present case shown as an integral part of the rearelement of the thrust bearing 58, having a ring 86 of friction materialsecured to its rear face as by means of rivets 88.

A member 90 suitably fixed to the forward face of the transmission frontwall 25 is provided with a forwardly projecting sleeve portion 92concentric with the axis of the shaft 28 and upon which is slidablyreceived a sleeve 94 provided at its forward end with a radiallyoutwardly extending flange 95, the forward face of which is formed andadapted for engagement with the friction ring 89. Suitably supportedwithin the bell housing 22 is the usual clutch shaft 98 provided withthe usual yoke I00 the free ends of which engage in diametricallyopposite pockets I02 formed on the sleeve 94. Exteriorly of the bellhousing 22 a clutch pedal I04 of conventional construction is secured tothe shaft 98.

Assuming that various parts of the clutch are in the position indicatedin Fig. 1, it will be apparent that the clutch is engaged so that anypower being exerted by the crank shaft ID will be directly transmittedthrough the shaft 28. As-

suming now that the clutch is turning in the direction previously notedand the parts are in the position indicated in Fig. 1, the flywheel,pressure plate 48 and driven disc 36 will all rotate in the samedirection at equal velocities and, because the ring member I4 is fixedfor equal rotation with the pressure plate", it will also turntherewith. Although the ring member I8 is free to rotate relative to theaxis of the sleeve I8, the ends of the fingers 54 in pressing rearwardlyagainst the thrust bearing 58 will urge the ring member 78 rearwardlyand tend to rotate the member 78 in a direction so as to reduce thecombined axial dimensions of the rings I4 and I8 to a minimum asindicated in Fig. 1 and, accordingly, the ring "i8 will also tend torotate with the ring I4 and the remaining parts of the clutch.

If now it is desired to disengage the clutch the upper end of the clutchpedal I94 is pressed forwardly causing the shaft 98 to be rocked in aclockwise direction as viewed in Fig. 1 and causing the free ends of theyoke I09 to urge the sleeve 94 forwardly and bring the forward face ofits flange 96 into contact with the friction ring 85 secured to the disc84. When this occurs the friction set up between the flange 99 and thering 85 will tend to retard the rotation of the disc 84 and consequentlythe ring 58 relative to the ring 14, and when such retardation occursthe balls 82 will roll toward the respective points of the cooperatingteeth I6 and 88 and thus force the ring members 14 and 18 axially awayfrom each other towards the position indicated in Fig. 4. The ring I4being maintained against axial rearward displacement, the ring I8 willmove forwardly with the thrust bearing 58 and cause the latter to pressagainst the inner ends of the clutch fingers 54 and cause such fingers54 to pivot about the forward edge of their respective openings 56 inthe clutch cover 42, and this movement of the fingers 54 acting throughthe nuts 98 and studs 52 will tend to cause the pressure plate 48 to bewithdrawn rearwardly against the force of the springs 59 so as to freethe clutch driven disc 39 between it and the web 54 of the flywheel,thus disengaging the clutch.

Obviously, if the pedal I04 is depressed only far enough to permit aninitial engagement of the flange 96 of the sleeve 94 with the frictionring 85 on the disc 84, and then is held in such position, only initialrotational movement of the ring I8 relative to the ring I4 will occurfor, as

soon as such partial rotation of the ring I8 occurs, it will draw awayfrom the flange 96 so as to relieve the friction between it and theflange 96, and as soon as such friction is relieved sufliciently topermit equal rotation of the rings I4 and I8, no further relativerotation of the ring 18 will occur. This partial relative rotation ofthe ring I8 may not be sufficient to cause release of the clutch but iffurther releasing movement of the clutch is desired all that isnecessary is to press the clutch pedal I94 a further amount to again setup sufficient friction between the flange and friction disc 86 to causea further relative rotation between the rings I4 and I8. Obviously, ifthe pedal I94 is depressed and continued pressure is applied thereto soas to cause the flange 85 to follow up forward movement of the frictionring 85 in moving forward with the ring I8, continued relative rotationof the ring 18 will occur until the clutch is moved to fully disengagedposi-, tion. In other words, to cause complete disengagement of theclutch the pedal I04 must be depressed sufficiently to bring the flange96 on the actual displacement of the ring I8. Conversely,

sleeve 94 into contactwith the friction ring 86 which is fixed'touthering I8 and the movement of the'pedal I04 must continue to follow up thewhen the clutch is fully released and'it is desired to re-engage it, theamount of re-engagement may be easily and accurately controlled by theamount which the clutch pedal I04 is allowed to return occur duringengagement thereof, thus permitting V I 1 the desired smoothacceleration of the vehicle in I trolled slippage of the clutch.

toward normal position, and bacause of this fact it Will be obvious thatthe pedal I04 may be so controlled by the operator that any amount ortdegree of slippage of the clutch maybe caused to which the clutch ismounted, through proper con- I It may be noted that sufficient relativerotation of the ring 18 to permit the balls to roll. over the high' endsof the, teeth I6 and 80 may be prevented in'any suitable manner, forinstance, as by providing astop for the pedal 104 to prevent, it frombeing movedrthrough a distance which "would be suflicient to cause'theballs 82 to roll' over the ends of the teeth. I Such a stop maytake'25...

the form of adjustable means supported either by the clutch housing I8or bell housing 22 but,

for the purpose of simplicity, it may be considered that the floor boardI06 contacting withthe pedal pad I08 of the pedal I04 will serve thedesired purpose and thus will limitthe movement of the ring I8 so asltoprevent the balls 82 from [rolling beyond the position indicated in Fig.4;

The rings I4 and I8, are, of course,.limited in their j relativerotation in the opposite direction by the balls 82 seating in theradiused surfaces 85 of the opposed members. It may also be noted that 1when the pedal pad I08 contactswith the floor 1 board I06 so as to movethe rings I4 and 18 to the .relative positions indicated in Fig. 4, the

'fiange 9 6 and friction ring 86 will simply slip rela tive'to oneanother without causing any added relative'rotation of the ring 18 whenthe clutch is in fully disengaged position. I

The amount of pressure which it is necessary to apply manually tothepedal I04 to retard the rotation ofthe ring I8 and to' move theclutch @to disengaged position, will vary in accordance with thediameter of the disc84 and the inclina tion of the teeth '80. Thediameter of the disc 84, for the purpose of compactness in arrangementof the clutch, is preferably kept at'a minimum, and it will berecognized that the inclination or V the teeth I6 and 80 must be such asto insure a complete disengagement of the clutch and at the same time besumcient to take care of normal wear of the clutch facing 38.

'With the construction of the rings I4 and I8 7 shown it will be notedthat each of the teeth 16 i so and 80 extends through approximately 180degrees of ang'ularity and that, in order to move the balls 82 fromsimultaneous contact with the radiused portions 85 onboth rings to aposition adjacent angle of approximately 360 degrees.

the tip; of cooperating teeth I6 and 80, the ring .18 must rotaterelative to the ring I4 through an recognized that if the teeth I6 andcontacted directly together without the interposition of rollinganti-friction means, then'the maximum rotation of the ring l8'withrespect to the ring I4 would be limitedeto the length of 'the'teeth;that is, in the present case substantially I degrees, the maximum'axialdisplacementwould belimited to the height of the teeth on one ring only,and in order toiget this movement the tip of one tooth would have toseatagainst the base of It will be the o posed tooth when the rings were "ina' position of minimum combined axial length. In

the present case it will benoted that the balls 82 r are seated at theopposed bases of the teeth ,16 and 80 when the rings are in a positionof minimum combined axiallength, and that when the ring I8 rotatesrelative to' the ring I4 the balls 82 roll circumferentially of therings at half the relative speed of their track on the ring"; The

result of this is a differential" action set up between the rings 14 andI8 and the balls.82flsuch that the ring 18 must turn'twice thelengthofthe teeth 80 in order to make the balls 82 roll the length of the teethI6, the balls .82 rolling along the teeth 80 at halfthe speed of thering 18 and By this simple means it is possible to obtain an" axialdisplacement of the rings "and I8 equal to twice the height of theirrespective teeth I6 and 80 and to travel through a' distance twice thelength of the teeth in being so displaced. As,

a result it will be apparent that the required axial displacementbetween the rings 14 and 18 is ob-' I required to retard rotation of:thering I8 in' a case Where the balls 62f were omitted and the teethallowed to slide directly on one anothen'this being true because theforce may act through twice the distance to perform the required work..

This amountof relative angular niovement'be;

- tween the rings 14 and I8 permits the angularity tained with buthalfof the force which would be of the teeth I6 and 80 to be suchthatarela- I tively small pressure between-the flange'96and:

friction member 86, and also on the pedal I04, is

sufficient to fully disengage the clutch, and this is particularly truein a smaller type of clutch. This light pressure on the pedal I04 will,in

1 many cases, induce the operator of the vehicle to hold the clutch outof engagement to permit the car tocoast without driving the engine; in

other words, to free wheel. ,It will be apparent that suchpractice onthe part of the operator will mean that the flange 96 and ring 86 arebeing pressed together and continually slipping relative I to eachother, but that sufficient friction is'being set up between them tomaintain the clutch dis-' engaged. In the lighterv types of clutchesthis friction may notbe great enough to resultin undue heating of thering 86 and flange. under such circumstances, but in the heavier sizesof clutches the pressure required to hold the clutch may be great enoughto cause sufiicient pressure on the ring 86 to burn it up. For thisreason it I V is extremely important that the inclination of the teeth16 and 80 be as small as possible so that the pressure required to beexertedv between the flange 96 and ring 86"to hold the clutch indisengaged position will be correspondingly low as will be the frictionset up'between the flange 96 and ring 86. At the same time, however theinclination of the teeth I6 and 80 must be'great enough to impartsufficient axial movement to the ring I8 to cause complete disengagementof the clutch even after a normal amount'of wear I of .the frictionrings. 7 V e e 7 h I have found itessential, particularly in thelargerclutches, to employ'not more than two l5 arriving at the tips of bothteeth simultaneously e tion is effective in holding the clutch fullyreleased as in using the clutch to free wheel, by further modifying theconstruction as indicated best in Fig. 3 in which it is shown applied tothe ring 18 only, it being understoood that the ring 14 is similarlyformed.

Referring to Fig. 3 it will be noted that the inclination of each tooth80 is relatively great adjacent the corresponding radius 85, and thatthe inclination of each tooth gradually decreases up to a point asubstantially midway its length, and from such point a to the tip of thetooth the inclination remains substantially constant at a relativelysmall value. Wit-h this construction the majority or even all of theaxial movement of the ring 18 may be obtained after a partial rotationalmovement only thereof, and after the balls 82 have reached the lowinclined outer ends of the teeth the ring 18 may be maintained in thisposition with an exceedingly small amount of pressure exerted betweenthe flange 85 and ring 86 with correspondingly small amount of frictionbetween them to cause heating thereof. By this means possibility ofburning up the ring 85 is effectively prevented but the pressure on thepedal I84 necessary to hold the clutch disengaged is also reduced and insome cases to such an extent that in order to obtain the proper feel ofthe clutch it is desirable to employ a spring such as 283 to constantlyurge the pedal I04 toward clutch engaged position.

It will be recognized by those skilled in the art that the abovedetails, while they may appear more or less trivial to those not skilledin the art, are, in reality, features that materially aid in making theclutch a commercially practicable structure.

From the structure thus far described it will be apparent that as far asthe operation thereof is concerned it has been considered necessary forthe driving member to be rotated in order to effect operation of theclutch. Occasions may arise wherein it is desirable to be able torelease the clutch when it is not rotating. This may be accomplished inthe structure shown in Figs. 1

to 5 inclusive by simply pressing down the pedal I64 which, actingthrough the sleeve 94 and flange 95, will move the disc 84 and thrustbearing 58 forwardly against the inner ends of the clutch fingers 54 torelease the clutch.

In the construction illustrated in Figs. 1 to 5 inclusive it will beapparent that the disc 84 in moving forwardly solely under the influenceof axial pressure from the sleeve 94 will carry with it the forward ring18 which is secured to the disc 84, and unless otherwise prevented thering 18 in moving forwardly with the disc 84 would pull away from thering 14 and leave the balls 82 free to move between them. In such casethe balls 82 might become displaced circumferentially of the teeth 16and 88 with the result that when the pedal IE4 is allowed to return tonormal position the balls 82 might prevent proper return movement of thering 18 to fully retracted position, and thereby interfere with theproper engagement of the clutch. As best indicated in Fig. 5, to guardagainst such possibility, a spring member in the form of a ring 1! isinterposed between the nut 12 and the ring 14, the ring 1I beingprovided with a plurality of circumferentially extending spring fingers13 which are bent laterally out of the plane of the ring 1I.' Thesefingers exert a relatively light pressure tending to separate the nut 12and ring 14 and normally are sprung into the plane of the ring 1Ithrough the pressure of the clutch fingers 54 acting through the thrustbearing 58 and intervening parts, but in the case where the ring 18 ismoved forwardly solely by axial pressure exerted through the sleeve 94the fingers 13 cause the ring 14 to follow the movement of the ring 18forwardly, as indicated in Fig. 5, and thus hold the balls 82 betweenthe rings 14 and 18 and prevent them from becoming displaced.

In Figs. 6 and 7 a modified form of structure is illustrated by means ofwhich a result equivalent to that obtained in the foregoing constructionis obtained with a considerably less number of parts. Referring to thesefigures it will be noted that an engine crankshaft I38 has secured toits rear end a flywheel including a web I32 and rim I54. A clutch shaftit has its reduced forward end suitably journaled in a bearing I38secured in a recess I48 in the rear end of the crank shaft I 35 andrearwardly thereof is splined as at I42 for non-rotatably but axially.slidably receiving the hub I44 of the clutch driven disc I46 providedwith friction facings I48 on its opposite faces. A clutch cover I58 issecured to the rear edge of the flywheel rim I34 by cap screws I52 andbetween the cover I58 and the clutch driven disc I46 is a pressure plateI54 which is maintained in concentric relation with respect to theclutch and supported therein for limited axial movement by spring strapsor links I56 each of which is secured at one end to the pressure plateI54 by cap screws I58 and at their opposite ends to the clutch cover I56by bolts: I68. These straps or links I56 form the subject matter of mycopending application for Letters Patent of the United States forimprovements in Clutches, filed August 5, 1933, Serial No. 683,719 andare fully disclosed therein. Preferably they are so tensioned as toconstantly urge the pressure plate I54 towards clutch disengagedposition. It is to be particularly noted that no packing springs orclutch fingers, such as the springs 58 and finger's'54 in Fig. l andtheir associated parts, are provided in this construction.

The clutch cover I58 and pressure plate I54 are provided with centralbushings I62 and I64 respectively in which is axially slidably receiveda sleeve member I66 on the rear end of which is meunted a disc memberI68 maintained against relative rearward displacement by means of a nutI18. Immediately inwardly of the clutch cover I56 there is fixed to theclutch cover I58 and relatively rotatable with respect to the sleeve I86 a ring member I 12, which may be considered as identical in allrespects to the ring member 14 described in connection with Fig. l andhaving inclined teeth I14 corresponding to the teeth 16 formed on itsforward side. Immediately forwardly of the ring I12 a ring I16 is fixedupon the sleeve I55 and this ring may be considered identical in allrespects to the ring 18 previously described and as having inclinedteeth I18 corresponding to the teeth 88 on the ring 18. Balls I85 aredisposed between the opposed teeth I14 and I18 and are maintained inoperative position.

the clutch cover I58 by means of a nut I94. Con-- A helical spring I88has its inner sidering the clutch to turn in the conventional dierection, the turns of the spring- I88 extend in a clockwise direction'as viewed in Fig; 7 and as ,traced in a direction from the outer end ofthe spring toward the inner end thereof. V a

o The discimember I68is provided on its forward face with a ring I96 offriction material,

' and positioned forwardly in advance of the disc I j I68 and normallyout of conta'ct'with the friction V ,which is formed for interengagementwith the friction disc; I96, and provided on diametrically ring I96 is aring member I98 the rear face of opposite sideswith radially projectingpins 200 adapted for eng' ageinent with the arms of a yoke 202corresponding to the yoke arms I09 previously described in connectionwithFig. 1 but adapted to V beoperated'in a rearward direction upondepression of the usual: clutch pedal corresponding to I the: pedal I04.In assembling this clutch the springfIBB' is given an initial tension ina directionsuch that it constantly urges the ring I16 in a clockwisedirection as viewed from the front .or the right hand end as viewed inFig. 6,'and this tends to rotate the ring I16 'in a clockwise directionrelativeto the ring IIZ as viewed from the rightvhandl -end of Fig; 6 soas to cause axial V displacement between the rings I12 and I15, urg- T1' ingthe ring I16 forwardly and, acting through the fthru st'bearingI84, forces the pressure plate I54 30 w between it and the web I32 ofthe flywheel. Con-' forwardly so. as;to clamp the-'drivendisc I46sequently, the spring I88 in acting through the ring I'IIi constantlyurges, the clutch toward en gaged position and maintains it in engagedposi 'tion except when otherwise controlled; Consider- 7 ing the clutchtobe in" the position indicated in Fig; 6,"it'wi1l be observed that ifthe ring I98 is moved 'rearwardly'z so as to cause it to engagethe'friction'ring I9,6,' the friction ring I98willberetarded.in'itsrotation and will cause a like balls Ian to rolltoward the bottomof 'theteeth approacheach'other in an axial directiondue to the action of the spring links I56 which constantly urge thepressure plate I 54 rearwardly, and thus will cause release of; theclutch. 7 By suitable manipulation 'of'the'clutch pedal the action ofthis clutch may be controlled 'in'substantially identical manner,as theclutch previously described may the foot pedal controlling'itwill haveto follow' ,be controlled. It will .be observed that in releasingthis'clutchthe ring I 98 and consequently the rearward movement of thedisc I58 and ring ,7 I16 to continue the releasing movement of the" iclutch in a manner equivalent'to that of the con r 6'0; 7 I V In orderto guard against possible displacement struction previously describe'd.

ofthespring I88 underthe influence of the cen- "trifugalforce which thespring is 'subjected to during rotation of the clutch, it may bedesirable the spring inorder to maintain it in its proper position. Suchmeans may. take theform of stop 1 pins 204 suitably fixed in the clutchcover I50 r ;I n bo th ofthe above described mechanisms it to'providemeans inthe form of abutments for and positioned in approximate contacti with the jouterturnlof the spring I88 adj accnt its free end asillustrated in Fig; 7. i 1

willibelapparent thatthe pressure which it is necessary'to manuallyapply to the clutch pedal order tobring the braking surfaces of the camring into sufilcient engagement tocause ac tuation of the cam rings, isrelatively small and but a small percentage of the pressure which it isnecessary to apply in manually controlled clutches of conventionalconstruction, and that at the same time by the means provided it ispossible to control the clutch just as precisely and accurately as suchconventional clutches maybe controlled by the foot in ordinarypractice.

Formal changes may be made in the'specific embodiments of the inventiondescribed without departing from the spirit or substance of the broadinvention, the scope of which' is commensurate with the appendediclaims.

Iclaim: r f 1. In a clutch structure, in combination, a driving element,a driven element; apressure'plate adapted to clamp said driven elementto said driv ing element, spring means constantly urging said pressureplate toward 7 clamping position, clutch fingers associated with saidpressure plate operable to move said pressure plateaway from clampingposition against the force of said spring means,

' a member constantly rotatable with said driving element and providedon an axially facing surface cooperatively associated with said inclinedteeth on the first mentioned member whereby relative rotation betweensaid members 'efiects bodily movement of the, second mentioned member,said second mentioned member being'operatively associated with saidclutch fingers whereby said bodily movement will causefactuation of saidfingers to move'said pressure plate away fro'm with axially inclinedteeth, asecond member nor; mally rotatable with said driving element butro-' c tatable relative thereto and having-inclined teeth clampingposition, and means frictionally associated with said secondmentioned'memberfor causing it to rotate relative to the first mentionedmember during rotation of said driving element including'a part bodilymovable with said second member, a second part non-rotatablebut axiallymovable into frictional engagement with the first mentioned part, andmeans for controlling the 1 axial position of said second part wherebyto per-' mitit to follow up thebodily displacing movement of saidsecondpart and thereby govern the 7 'amount of axial displacement ofsaid second member. i

V 2. Ina clutch structure, in combination, a driving member, a drivenmember, a pressure plate adapted to clamp said driven member to saiddriving membenrand means for releasing said pressure, plate fromclamping position including a pair of relatively rotatable members one,of which is driven directly by said driving member and havingcooperating axially inclined surfaces, said surfaces having a greaterinclination atone end thereof than at. the other end thereof,antifriction means disposed between cooperating and opposed saidsurfaces, and means for effecting relmembers.

'3, In a clutch structure in combination, ardriying element, a drivenelement, a pressure plate 7 adapted to clamp said driven element tosaiddriv ative rotation between said relatively, rotatable ing element,spring means constantly urging said,

pressure plate toward clamping position, clutch ,fingersassociated withsaidpressure plate oper- 70 able to move'said pressure plate away fromclamping position against the force of said spring;

means, a cam member constantly rotatable with said driving .element andprovided on an axially facing surface thereof with axially inclinedteeth,

a second cam member'normally rotatable with said driving element butrotatable relative thereto and having inclined teeth cooperativelyassociated with said inclined teeth on the first mentioned cam memberwhereby relative rotation between said cam members effects bodilymovement of the second mentioned cam member, antifriction meansinterposed between said inclined teeth, said second mentioned cam memberbeing operatively associated with said clutch fingers whereby saidbodily movement thereof will cause actuation of said fingers to movesaid pressure plate away from clamping position, and means frictionallyassociated with said second mentioned cam member for causing it torotate relative to the first mentioned member during rotation of saiddriving element, the inclination of said inclined surfaces being suchthat said second mentioned cam member is reversible in movement solelyunder the influence of said clutch fingers.

4. In a clutch structure, in combination, a driving element, a drivenelement, a pressure plate adapted to clamp said driven element to saiddriving element, spring means constantly urging said pressure platetoward said clamping position, a member rotatable with said drivingelement but axially slidable relative thereto, means limiting axialmovement of said member in one direction, spring means constantly urgingsaid member axially away from said limiting means, a second memberrelatively rotatable with respect to the first mentioned member,anti-friction means interposed between said members, said members beingso formed and so cooperating with each other that relative rotationbetween them effects axial advancement of said second member relative tothe first mentioned member, means operatively connecting said secondmember and said pressure plate for correlated movements, a part axiallyand rotatably movable with said second member, a second non-rotatablepart movable axially of said clutch and arranged for frictionalengagement with the first mentioned part, and means for controlling theaxial position of said 1 second part.

5. In a clutch structure, in combination, a driving element, a drivenelement, a pressure plate, spring means constantly urging said pressureplate toward a position to clamp said driven element to said drivingelement, means for retracting said pressure plate against the force ofsaid spring means including a pair of members one of which is constantlyrotatable with said driving element but axially movable relativethereto, an abutment limiting axial movement of said member in onedirection, spring means interposed between said abutment and said membertending to separate them axially, the other of said members beingrotatable, and axially movable relative to the first mentioned memberand said members having cooperating axially inclined surfaces thereon,rolling anti-friction means between said surfaces, means operativelyconnecting said other of said members with said pressure plate forinterrelated movement, a friction member secured for equal rotation withsaid other of said members, and manually controllable means engageablewith said friction member for retarding rotation thereof during rotationof said driving element.

6. In combination, a driving element, a driven element frictionallyengageable therewith, means for moving one of said elements bodilyrelative to the other thereof to control said frictional en- I gagementincluding a pair of relatively rotatable members one of which is drivenby said driving element and the other of which is cooperativelyassociated with said driven element, said members being so formed and socooperating with each other that relative rotation between them effectsaxial movement of one with respect to the other, an abutment limitingaxial movement of one of said members in one direction, spring means interposed between said abutment and the cooperating one of said members,a part rotatable and axially movable with said cooperating member, amovable second part frictionally engageable with the first mentionedpart, and means for controlling the movable position of said secondpart.

7. In combination, a driving element, a driven element frictionallyengageable therewith, means for moving one of said elements bodilyrelative to the other thereof to control said frictional en gagementincluding a pair of relatively rotatable members one of which is drivenby said driving element and the other of which is cooperativelyassociated with said driven element and having cooperating axiallyinclined surfaces, said surfaces having a greater inclination at one endthereof than at the other end thereof, and means for effecting relativerotation between said relatively rotatable members.

8. In a clutch structure, in combination, a driving element, a drivenelement, means for connecting said elements together in drivingengagement, and means for variably controlling the establishment ofdriving engagement between said elements, comprising a member constantlydriven by said driving element, a second member movable for variablycontrolling said driving engagement in proportion to its movement, saidmembers having cooperating cam means formed on axially opposed surfacesthereof so constructed and arranged with respect to each other as topermit substantially not less than 360 of rotation of one member withrespect to the other thereof in moving from one limit of position ofmovement to the other limit thereof, and means for controlling therelatively rotatable positions of said members.

9. In combination, a driving element, a driven element frictionallyengageable. therewith, means for moving one of said elements bodilyrelative to the other thereof to control said frictional en- T gagementincluding a pair of relatively rotatable members one of which is drivenby said driving element and the other of which is cooperativelyassociated with said driven element, said members being so formed and socooperating with each other that relative rotation between them effectsaxial movement of one with respect to the other, an abutment limitingaxial movement of one of said members in one direction, spring means interposed between said abutment and the cooperating one of said memberscomprising an annulus abutting said abutment and having axially inclinedcircumferentially extending spring fingers contacting said one of saidmembers, a part rotatable and axially movable with said cooperatingmember, a movable second part frictionally engageable with the firstmentioned part, and means for controlling the movable position of saidsecond part.

10. In a clutch structure, in combination, a driving element, a coaxialdriven element, a driven shaft secured to said driven element in coaxialrelation therewith and extending axially away therefrom, a pressureplate rotatable with said driving element, means constantly urging saidpressure plate toward a position to clamp said driving anddriven'elements together foriequal rotation,ra sleeve surrounding saiddriven shaft and associated with said pressure plate for equal rotationtherewith, ran abutment on the endof said sleeve more remote from saidpressure plate, a member'surrounding and normally rotatable with saidsleeve and maintained against axial displacement in one direction bysaid abutment, a second member rotatably and slidably surrounding saidsleeve'between the first mentioned member and said pressure plate, saidmembers being so constructed and arranged that relative rotation"between them effects axial displacement of one with respectto theother, means interconnecting said second member and said pressure platefor interrelated movementsga'nd 'means frictionally associated with saidsecond member'for controlling the relative rotation between it and thefirst 'mentioned member. r 1

I V 11, In aclutch structure, in combination, a:

' drivingelemenfia coaxial driven element, a driven shaft secured tosaid driven element in;coaxial "relation therewith and extendingaxiallyaway therefrom, a pressure plate rotatable with said driving element,means constantlyfurging said pressure plate toward a position toclampsaid 7 driving and driven elements together for equal rotation, asleeve surrounding said driven shaft 7 andassociated' with said pressureplatefor equal 7 rotation therewith,-an' abutment'on the end of saidsleeve more remote from said pressure plate, a member surroundingand'norrnally rotatable with said sleeve and maintained against axialdispla'cement'in one direction by said abutment, a second memberrotatably and'slidably surround- V ingsaid sleeve between the firstmentioned mem non-rotatably associated with said second memtionelementmovable axially with respect to the,

150 first mentioned friction element, and manual ber and said pressureplate, said members being so constructed and arranged that relativerotation between them effects axial displacement of one with respect tothe other, means interconnecting said second member and saidp'ressureplate for interrelated movements, and means frictionallyassociated withsaid second memberfor' controlling the relative rotationbetween it and the first mentioned member, including a friction elementber and axially movable therewith, a secondfric-i means for controllingsaid second frictional element enabling follow up movement thereof withI respect to said first'mentioned friction element.

12. In a clutchstructure, in combination a driving element, a drivenelement, a pressure plate rotatable equall'y with said driving element;

- spring means constantly urging said pressure plate away from clampingrelation with respect to said driven element, a member rotatable equallywith said driving element and maintained against axial movement in onedirection relative thereto, said member having, axially inclinedsurfaces, formed thereon, a second member rotatable and axially movablerelative to the first mentioned memberhavin g inclined surfaces thereoncooperating with said inclined surfaces to impart axial movement to saidsecond member when rotated plate for'equal axial movement therewith inat least one direction, spring means constantly urging said secondmember toward saiddirection of:

rotation whereby to force said'pressureplate to a position to clamp saiddriven element tosaid to said driven element, a member rotatable equallyino'ne direction relative thereto, said secondmem ,ber'being operativelyconnected to said pressure driving'element in opposition to the firstmentioned spring means, and manually controllable means for overcomingthe force of the second mentioned spring means.

I 13. Ina clutchstructure, in combinatioma 5 axially movable relativeto'the first mentioned member having inclined surfaces thereoncooperating with said inclined surfaces to impart axial V movementtoisaid second member when rotated; in one direction relative thereto,said second member being operatively connected to said pressure plateforequal axial movement therewith in at least one direction, springmeans constantly urging said second member toward said'direction' ofrotation whereby to force saidpressure plate to V a position to clampsaid drivenfelement to said driving element in'oppositio'n to the firstmentioned spring means, and manually controllable means for overcomingthe force of the second mentioned spring means including a part axiallyV movable with said second member and'a man'- a ually controllable partmovable into frictional engagement with the first mentioned part. V a

14. In a clutch structure, in combination, a

driving element, a driven element, an element movable to clamp saiddriven element to said'35 driving element for equal rotation therewith,a

cover element" fixed to said driving element and" enclosing said drivenelement and said movable element between it and said driving element,cam 7 means fixed to said cover element,;cam means 00- 40 operativelyassociated with thefirst mentioned. cam means androtatable relativethereto inter posed between said first mentioned cam means andrsaidmovable member, said cam means'being so, constructed and arranged thatrotation ,of

one with respectto the other effectsaxial displacement of one withrespect to the other, a spiral. spring concentrically arranged withrespect to said driven'shaft havingone end thereof fixed Q with respectto said driving member and the other end thereof operatively connectedwith the second mentioned cam means'and constantly urging said secondmentioned cam means in one direction of rotation with respect to saidfirst mentioned cam 7 means, manually operable means for overcoming saidspring at will, and means cooperating be,, tween said cover element and'said spring for limiting the displacing effects of centrifugal force 7on said spring. I V a V 15. In a clutch *structure, in combination, a601driving element, a driven element, an element movable to clamp saiddriven 'element to said driving element for equal rotation therewith, a7

7 cover element fixed to said driving element and enclosing said drivenelement and said movable element between it and said'driving element,cam means fixed to said cover element, oam' means cooperativelyassociated with the first mentioned cam means and rotatablerelative'thereto interposed'between said first mentioned cam meansand'said movable element, said cam'means-being so constructed andarranged that rotationlof one j with respect to the other effects axialdisplace- 7 ment of one with res'pectto the'other, yieldable meansenclosed between said coverelement'and said driving element for urgingthe second mentioned cam means in a direction of rotation relative tosaid first mentioned cam means whereby to effect axial separatingmovement of said cam means and thereby urge said movable element towardclamping relation with respect to said driven element, and meansextending to the exterior of said cover operatively connected to saidsecond mentioned cam means and operable to overcome the tendency of saidyieldable means thereon and effect relative rotation thereof in adirection opposite to that urged by said yieldable means.

16. In a clutch structure, in combination, a driving element, a drivenelement, an element movable to clamp said driven element to said drivingelement for equal rotation therewith, a cover element fixed to saiddriving element and enclosing said driven element and said movableelement between it and said driving element, cam means fixed to saidcover element, cam means cooperatively associated with the firstmentioned cam means and rotatable relative thereto interposed betweensaid first mentioned cam means and said movable element, said cam meansbeing so constructed and arranged that rotation of one with respect tothe other effects axial displacement of one with respect to the other,yieldable means enclosed between said cover element and said drivingelement for urging the second mentioned cam means in a direction ofrotation relative to said first mentioned cam means whereby to eifectaxial separating movement of said cam means and thereby urge saidmovable element toward clamping relation with respect to said drivenelement, means connected with said second mentioned cam means andmovable axially therewith extending exteriorly of said cover, a frictionelement secured to said connecting means exteriorly of said cover, andmanually controllable means cooperatively associated with said frictionelement to modify the rotational movements thereof.

17. In a clutch structure, in combination, a driving element, a drivenelement, an element movable to clamp said driven element to said drivingelement for equal rotation therewith, a cover element fixed to saiddriving element and enclosing said driven element and said movableelement between it and said driving element, cam means fixed to saidcover element, cam means cooperatively associated with the firstmentioned cam means and rotatable relative thereto interposed betweensaid first mentioned cam means and said movable element, said cam meansbeing so constructed and arranged that rotation of one with respect tothe other effects axial displacement of one with respect to the other,yieldable means enclosed between said cover element and said drivingelement for urging the second mentioned cam means in a direction ofrotation relative to said first mentioned cam means whereby to effectaxial separating movement of said cam means and thereby urge saidmovable element toward clamping relation with respect to said drivenelement, means connected with said second mentioned cam means andmovable axially therewith extending exteriorly of said cover, an axiallyfacing friction element secured to said connecting means exteriorly ofsaid cover and axially movable therewith, and manually controllablemeans adapted for engagement with said V friction element and movable infollow-up relation therewith to modify the rotational movements of saidsecond mentioned cam means.

18. In a clutch structure, in combination, a driving element, a drivenelement, an element movable to clamp said driven element to said drivingelement for equal rotation therewith, a cover element fixed to saiddriving element and enclosing said driven element and said movableelement between it and said driving element, cam means carried by saidcover element and maintained against axial displacement in one directionthereby, cam means cooperatively associated with the first mentioned cammeans and rotatable relative thereto, anti-friction means interposedbetween the second mentioned cam means and said movable member, said cammeans being so constructed and arranged that rotation of one thereofwith respect to the other thereof in at least one direction effectsaxial displacement of one with respect to the other, yieldable meansconstantly urging the second mentioned cam means in a direction ofrotation relative to said first mentioned cam means whereby to effectaxial separating movement of said cam means and thereby urge saidmovable element toward clamping relation with respect to said drivenelement, a member fixed against rotation with respect to said secondmentioned cam means extending through said cover and having axiallyslidable bearing therein, an axially facing friction element secured tothe last mentioned member exteriorly of said cover, a second axiallyfacing friction element interposed between said cover and the firstmentioned friction element, and means for controlling the axial positionof said second mentioned friction element.

19. In a clutch structure, in combination, a driving element, a drivenelement, a pressure plate fixed for equal rotation with said drivingelement and movable axially with respect to both said driving and drivenelements, spring means constantly urging said pressure plate toward aposition to clamp said driven element to said driving element for equalrotation therewith, fingers cooperating between said driving member andsaid pressure plate for moving said pressure plate away from saidclamping position against the force of said spring means, and means foractuating said fingers including a pair of relatively rotatable memberscoaxial with said elements and having axially opposed and axiallyinclined cooperating cam surfaces, means limiting rearward movement ofone of said members, the other of said members being free to moveforward and cooperating with said fingers when operated to move saidfingers toward clutch released position, and manually operated meanscooperating with said other of said members in follow up relation withrespect thereto for applying power from said driving element thereto toeffect relative rotation thereof with respect to said one of saidmembers to thereby effect release of said clutch.

ROBERT C. RUSSELL,

